82 SOUTH AFRICAN FLOWERING PLANTS. 



support themselves ; consequently, to prevent falling, 

 they put on " supportive tissues," of which wood-fibres 

 are the most important. But as the water helps to 

 support a submerged stem, which is also filled with 

 air, there is no necessity for much, if any, wood. As 

 a result it is not developed. The general effect of a 

 submerged life is a " degeneration " by the arrest of the 

 formation of internal supportive tissues, and in other 

 ways. 



The Water-lily's leaves and flowers arise from a 

 thick, horizontal stem called a Rhizome. If a section 

 of this be made, the " woody bundles " do not form a 

 ring, but are scattered about, like those in a stick of 

 asparagus, or as described in speaking of the stem of 

 Monocotyledons.^ 



General Descri;ption of the Water -lily Family. 



Herhs — Aquatic, with thick rhizomes. 



Leaves — Mostly floating, with cordate'^ or peltate^ 

 blades. 



Flowers — Petals numerous, passing into stamens; 

 carpels, numerous, syncarpous, within a fleshy disc. 



1 See p. 71. ^ le. heart-shaped. 



3 I.e. shield-like, the petiole entering the middle of the blade. 



